Search Results (67)

This study evaluated birch and oak ash extracts as alternative extractants for isolating humic substances (HSs) from peat and lignite. The effects of ultrasound intensity, extraction time, and temperature were optimized using a Box–Behnken design and validated statistically. The highest HSs yields were obtained from peat with oak ash extract (pH 13.18), compared to birch ash extract (pH 12.09). Optimal process parameters varied by variant, falling within 309–391 mW∙cm⁻², 116–142 min, and 67–79 °C. HSs extracted under optimal conditions were fractionated into humic acids (HAs) and fulvic acids (FAs), and then analyzed by elemental analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Cross-Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance Spectroscopy (CP/MAS ¹³C NMR). The main differences in HSs quality were influenced by raw material and fraction type. However, the use of birch ash extract consistently resulted in a higher proportion of carboxylic structures across all fractions. Overall, wood ash extract, especially from oak, offers a sustainable and effective alternative to conventional extractants, particularly for HSs isolation from lignite. Notably, HSs yield from lignite with oak ash extract (29.13%) was only slightly lower than that achieved with 0.5 M NaOH (31.02%), highlighting its practical potential in environmentally friendly extraction technologies. Full article

To address the challenges of concrete construction in polar regions, this study investigates the feasibility of fabricating cement-based materials under severely low temperatures using electric-induced heating curing methods. Cement mortars incorporating fly ash (FA-CM), ground granulated blast furnace slag (GGBS-CM), and metakaolin (MK-CM) were cured at environmental temperatures of −20 °C, −40 °C, and −60 °C. The optimal carbon fiber (CF) contents were determined using the initial electric resistivity to ensure a consistent electric-induced heating curing process. The thermal profiles during curing were monitored, and mechanical strength development was systematically evaluated. Hydration characteristics were elucidated through thermogravimetric analysis (TG), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) to identify phase compositions and reaction products. Results demonstrate that electric-induced heating effectively mitigates the adverse effect caused by the ultra-low temperature constraints, with distinct differences in the strength performance and hydration kinetics among supplementary cementitious materials. MK-CM exhibited superior early strength development with strength increasing rates above 10% compared to the Ref. specimen, which was attributed to the accelerated pozzolanic reactions. Microstructural analyses further verified the macroscopic strength test results that showed that electric-induced heating curing can effectively promote the performance development even under severely cold environments with a higher hydration degree and refined micro-pore structure. This work proposes a viable strategy for polar construction applications. Full article

Natural phosphate ores frequently contain calcium–magnesium carbonate minerals as gangue components. Their separation from target phosphate minerals poses significant challenges due to analogous surface characteristics. The flotation differentiation between fluorapatite and dolomite remains a key research focus in mineral processing. In conventional collector systems, selective depressants critically govern separation efficiency, as their interfacial specificity directly determines beneficiation outcomes. The selective depression behavior of fulvic acid (FA) in modulating fluorapatite–dolomite separation efficiency within oleate-dominated flotation systems was elucidated through micro-flotation experiments, complemented by zeta potential measurements, contact angle analysis, Fourier-transform infrared spectroscopy (FTIR), and molecular dynamics (MD) simulations. The findings revealed that fluorapatite and dolomite both exhibit high floatability under NaOl-mediated collector systems in the absence of depressant additives, leading to negligible selectivity in the differential separation of the mineral pair. However, the float of fluorapatite particles in weakly acidic conditions was strongly depressed when a small amount of FA was added as a depressant, while exerting minimal impact on dolomite’s floatability. In binary artificial mixed-mineral flotation systems, under optimized flotation conditions (pH 5.0, 60 mg/L NaOl, and 15 mg/L FA), the concentrate achieved a P₂O₅ grade of 33.86% with a fluorapatite recovery rate of 92.36%, demonstrating significant selective separation of fluorapatite from dolomite. Subsequent analysis revealed that FA competitively chemisorbs with NaOl on fluorapatite surfaces, selectively reducing the hydrophobicity of the fluorapatite surface and suppressing fluorapatite floatability, thereby enabling effective differential liberation of the mineral pair. Full article

Using industrial byproducts to replace cement is an important way to reduce carbon emissions from the cement industry. In this study, the effects of two industrial byproducts, fly ash (FA) and quartz powder (QZ), as supplementary cementitious materials (SCMs) on the macroscopic properties and microstructure of cement-based materials were experimentally investigated. The results of the compressive strength and ultrasonic pulse velocity experiments showed that QZ significantly mitigated the decrease in strength and ultrasonic pulse velocity caused by the reduction in cement dosage in the early stage. Moreover, the 28-day compressive strength of the FA group was comparable to that of the control group, and regression analysis indicated a negligible effect of FA addition on 28-day compressive strength. X-ray diffraction and Fourier transform infrared spectroscopy experiments showed that QZ can promote the hydration reaction in the early stage. Scanning electron microscopy images revealed that a layer of hydration products can form on the surface of FA after 28 days of hydration. Hydration heat experiments indicated that FA significantly reduces the release of hydration heat, while QZ promotes the formation of ettringite through nucleation effects in the early stage of hydration, thereby accelerating the release of hydration heat. Thermogravimetric analysis after 28 days showed that the amount of hydration products and calcium hydroxide produced decreased with the addition of cementitious materials. Finally, the use of FA and QZ was analyzed for carbon emissions and energy consumption. The results showed that using these two cementitious materials significantly reduces carbon dioxide emissions and energy consumption. Full article

To address the issues of the low pozzolanic activity and high pollution potential of red mud (RM), this study utilizes different industrial solid wastes to synergistically enhance the physicochemical properties of red mud-based filling materials. The compressive strengths of red mud-based filling materials activated by three types of solid wastes—desulfurized gypsum (DG), carbide slag (CS), and steel slag (SS)—were compared, revealing the differences in their effects on the physicochemical properties of the materials. The results showed that DG significantly enhanced the compressive strength of the backfill material. The composite system composed of 65.8% RM, 18.8% FA, 9.4% cement, and 6% DG achieved a compressive strength of 7.36 MPa after 28 days of curing, demonstrating a 97.8% increase compared to the control group. Techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) analysis were employed to characterize the microstructural evolution of the red mud-based filling materials activated by different solid wastes. This study investigated the differences in the pore structure, microscopic morphology, and chemical composition of the materials containing different solid wastes. The results indicated that DG effectively promotes the formation of ettringite and C(-A)-S-H gel, optimizes the pore structure of the filling materials, and forms a dense matrix, thereby enhancing the stiffness and strength of the materials. Additionally, the red mud-based filling materials developed in this study exhibit excellent environmental performance. This not only provides theoretical support for the development of red mud-based filling materials but also offers new insights for mine backfilling and the co-disposal of solid wastes. Full article

Background: Folic acid (FA) is essential for cellular functions but has limited ocular bioavailability, restricting its therapeutic effectiveness. Objective: To develop chitosan (CS)-based nanogels (NGs) for FA transport and release, with corneal permeation evaluation. Methods: NGs’ hydrodynamic diameter (Ho) and polydispersity index (PdI) were determined using dynamic light scattering (DLS). CS-FA interaction was confirmed by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) was applied for the dehydrated material characterization. Scanning electron microscopy (SEM) was used to evaluate the NGs ultraestructure. In vitro drug release studies were performed using a modified Franz diffusion cell, and the release profile was fitted to obtain kinetics parameters. Mucoadhesion properties were evaluated through ζ-potential measurements. Ex vivo corneal permeation studies were conducted in rabbit corneas to compare the permeability of FA contained in NGs. Results: NGs presented a Ho of 312.4 ± 8.2 nm and a PdI of 0.28 ± 0.04. SEM imaging revealed spherical morphologies with minor variations in size and shape induced by FA. Lyophilized and resuspended NGs exhibited a 6.8% increase in Ho and a PdI rise to 0.42, indicating slight aggregation. In vitro drug release studies demonstrated sustained FA release, as determined by the Higuchi model. Mucoadhesion studies showed a decrease in ζ-potential from +36.9 to +18.1 mV, confirming electrostatic interactions with mucin. Ex vivo corneal permeation studies indicated that encapsulated FA permeated 2.6 times slower than free FA, suggesting sustained release. Conclusions: our findings demonstrate the potential of nanostructures in the form of NGs to enhance FA-loaded ocular delivery and bioavailability. Full article

This study systematically investigates the rheological modification mechanism of steel slag powder (SSP) as an alternative filler in asphalt mastics, with comparative analysis against conventional limestone powder (LP). Four filler-to-asphalt (F/A) ratios (0.6–1.2) were employed to prepare modified mastics. Comprehensive characterization through laser diffraction analysis, BET nitrogen adsorption, and scanning electron microscopy (SEM) revealed SSP’s significant microstructural advantages: a 29.2% smaller median particle size (D50) and 7.06% larger specific surface area compared to LP, accompanied by enhanced interparticle connectivity and morphological complexity. Rheological evaluation via dynamic shear rheology (DSR) demonstrated SSP’s superior performance enhancement—particularly at elevated F/A ratios (1.0–1.2), where multiple stress creep recovery (MSCR) tests showed a 6.9–46.06% improvement in non-recoverable creep compliance (J_nr) over LP-modified counterparts. The temperature sweep analysis indicated SSP’s effectiveness in reducing the temperature susceptibility index by 9.37–18.06% relative to LP. Fourier-transform infrared spectroscopy (FTIR) combined with two-dimensional correlation analysis (2D-COS) confirmed the dominance of physical interactions over chemical bonding in the SSP–asphalt interface. The results establish SSP’s dual functionality as both a rheological modifier and sustainable construction material, providing mechanistic insights for optimizing steel slag utilization in pavement engineering. Full article

Kefir, a fermented milk product produced using kefir grains, is a symbiotic consortium of bacteria and yeasts responsible for driving the fermentation process. In this study, an in-depth analysis of kefir’s lipid profile was conducted, with a focus on its phospholipid (PL) content, employing liquid chromatography with high-resolution mass spectrometry (LC-HRMS). Nearly 300 distinct polar lipids were identified through hydrophilic interaction liquid chromatography (HILIC) coupled with electrospray ionization (ESI) and Fourier-transform orbital-trap MS and linear ion-trap tandem MS/MS. The identified lipids included phosphatidylcholines (PCs), lyso-phosphatidylcholines (LPCs), phosphatidylethanolamines (PEs) and lyso-phosphatidylethanolamines (LPEs), phosphatidylserines (PSs), phosphatidylglycerols (PGs), and phosphatidylinositols (PIs). The presence of lysyl-phosphatidylglycerols (LyPGs) was identified as a key finding, marking a lipid class characteristic of Gram-positive bacterial membranes. This discovery highlights the role of viable bacteria in kefir and underscores its probiotic potential. The structural details of minor glycolipids (GLs) and glycosphingolipids (GSLs) were further elucidated, enriching the understanding of kefir’s lipid complexity. Fatty acyl (FA) composition was characterized using reversed-phase LC coupled with tandem MS. A mild epoxidation reaction with meta-chloroperoxybenzoic acid (m-CPBA) was performed to pinpoint double-bond positions in FAs. The dominant fatty acids were identified as C18:3, C18:2, C18:1, C18:0 (stearic acid), C16:0 (palmitic acid), and significant levels of C14:0 (myristic acid). Additionally, two isomers of FA 18:1 were distinguished: ∆9-cis (oleic acid) and ∆11-trans (vaccenic acid). These isomers were identified using diagnostic ion pairs, retention times, and accurate m/z values. This study provides an unprecedented level of detail on the lipid profile of kefir, shedding light on its complex composition and potential nutritional benefits. Full article

Despite the interaction between polyphenols and polysaccharides in food products, their specific non-covalent interactions and effects on macrophage functions are not well understood. Therefore, the interaction and mechanism of purified lotus root polysaccharide (PLRP) with polyphenols, and the regulatory mechanisms of the PLRP-polyphenol complex on the macrophage functionals were studied. By combining ferulic acid (FA) and chlorogenic acid (CHA) with PLRP, the complexes PLRP-FA, PLRP-CHA and the physical mixtures PLRP&FA and PLRP&CHA were prepared, where their mass ratios of polyphenols to PLRP were 143.97 and 601.67 mg g⁻¹. Nuclear magnetic resonance (NMR), Fourier-transform infrared (FTIR), Ultraviolet (UV), and Transmission electron microscopy (TEM) analyses confirmed that PLRP and polyphenols may engage in non-covalent interactions via hydrogen bonds and hydrophobic interactions. We confirmed that non-covalent interactions led to high molecular weight, dense complexes. Both PLRP and its polyphenol complexes stimulated NO production by macrophages to varying degrees without exacerbating lipopolysaccharide-induced inflammatory responses. PLRP and PLRP-polyphenol complexes repaired cells with impaired antioxidant capacity, depending on doses. Those results indicated that after the combination of lotus root polysaccharide and polyphenol, the molecular weight and conformation changed significantly, which influenced the biological activity. RNA-seq analysis suggested that the regulatory mechanism of PLRP-polyphenol complex in macrophages may mainly involve oxidative phosphorylation, FoxO, TNF, IL-17, MAPK, NF-kappa B, and other signaling pathways. This study investigated the effects of polyphenol binding on the physicochemical characteristics and functional activities of polysaccharides, which provided references for the development of polysaccharide functional products and the control of nutritional quality. Full article

Pervious concrete, because of its high porosity, is a suitable material for reducing the effects of water precipitations and is primarily utilized in road pavements. In this study, the effects of binder-to-aggregate (B/A) ratios, as well as mineral admixtures with and without polypropylene fibers (PPFs) (0.2% by volume), including fly ash (FA) or silica fume (SF) (10% by substitution of cement), on the mechanical properties and durability of pervious concrete were experimentally observed. The experimental campaign included the following tests: permeability, porosity, compressive strength, splitting tensile strength, and flexural strength tests. The durability performance was evaluated by observing freeze–thaw cycles and abrasion resistance after 28 d curing. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA-DTA), and scanning electron microscopy (SEM) combined with energy dispersive spectroscopy (EDS) were employed to investigate the phase composition and microstructure. The results revealed that, for an assigned B/A ratio identified as optimal, the incorporation of mineral admixtures and fibers mutually compensated for their respective negative effects, resulting in the effective enhancement of both mechanical/microstructural characteristics and durability properties. In general, pervious concrete developed with fly ash or silica fume achieved higher compressive strength (>35 MPA) and permeability of 4 mm/s, whereas the binary combination of fly ash or silica fume with 0.2% PPFs yielded a flexural strength greater than 6 MPA and a permeability of 6 mm/s. Silica fume-based pervious concrete exhibited excellent performance in terms of freeze–thaw (F-T) cycling and abrasion resistance, followed by fiber-reinforced pervious concrete, except fly ash-based pervious concrete. Microstructural analysis showed that the inclusion of fly ash or silica fume reduced the harmful capillary pores and refined the pore enlargement caused by PPFs in the cement interface matrix through micro-filling and a pozzolanic reaction, leading to improved mechanical and durability characteristics of pervious concrete. Full article

In cold regions, saline soils can cause dissolution, settlement, and salt expansion of the roadbed under the influence of freeze–thaw cycles, so they need to be stabilized during road construction. In this study, lime, fly ash (FA), and polyacrylamide (PAM) were used to stabilize sulfate saline soils, and the stabilized saline soils were subjected to the unconfined compressive strength test (UCS), splitting test, and freeze–thaw cycle tests (FTs). The stabilization mechanism of the three materials on saline soils was also studied via scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and X-ray photoelectron spectroscopy (XPS). The test results showed that the addition of lime, FA, and PAM to saline soils can improve the mechanical properties and frost resistance of saline soils. After 28 d of curing, the UCS of FA-, PAM-, and lime-stabilized saline soils increased by at least 55%, 23%, and 1068%, respectively, and the splitting strength increased by at least 161%, 75%, and 2720%, respectively. After five freeze–thaw cycles, the residual strength ratios (BDRs) of the UCS of L2 (lime 8%), F2 (FA 11%), and P2 (PAM 1%) stabilized soils and saline soils were 71.78%, 56.42%, 39.05%, and 17.95%, respectively, and the decreasing trend tended to be stable. The saline soils stabilized by lime and FA were chemically stabilized, and their mechanical properties and frost resistance were better than the physical stabilization of PAM. Full article

The consecutive submesoscale sea surface processes observed by an unmanned aerial vehicle (UAV) were used to decompose into spatial waves and current features. For the image decomposition, the Fast and Adaptive Multidimensional Empirical Mode Decomposition (FA-MEMD) method was employed to disintegrate multicomponent signals identified in sea surface optical images into modulated signals characterized by their amplitudes and frequencies. These signals, referred to as Bidimensional Intrinsic Mode Functions (BIMFs), represent the inherent two-dimensional oscillatory patterns within sea surface optical data. The BIMFs, separated into seven modes and a residual component, were subsequently reconstructed based on the physical frequencies. A two-dimensional Fast Fourier Transform (2D FFT) for each high-frequency mode was used for surface wave analysis to illustrate the wave characteristics. Wavenumbers (K_x, K_y) ranging between 0.01–0.1 radm⁻¹ and wave directions predominantly in the northeastward direction were identified from the spectral peak ranges. The Optical Flow (OF) algorithm was applied to the remaining consecutive low-frequency modes as the current signal under 0.1 Hz for surface current analysis and to estimate a current field with a 1 m spatial resolution. The accuracy of currents in the overall region was validated with in situ drifter measurements, showing an R-squared (R²) value of 0.80 and an average root-mean-square error (RMSE) of 0.03 ms⁻¹. This study proposes a novel framework for analyzing individual sea surface dynamical processes acquired from high-resolution UAV imagery using a multidimensional signal decomposition method specialized in nonlinear and nonstationary data analysis. Full article

Graphene has become a prominent material in cancer research in recent years. Graphene and its derivatives also attract attention as carriers in drug delivery systems. In this study, we designed a graphene oxide (GO)-based methotrexate (MTX)-loaded and folic acid (FA)-linked drug delivery system. MTX and FA were bound to GO synthesized from graphite. MTX/FA/GO drug delivery system and system components were characterized using Fourier transform infrared spectroscopy (FTIR), differential calorimetric analysis (DSC), scanning electron microscopy (SEM), transmission electron microscopy (TEM), zeta potential analysis, and dimension measurement (DLS) studies. SEM and TEM images confirmed the nanosheet structure of GO synthesized from graphite, and it was shown that MTX/FA binding to GO transformed the two-dimensional GO into a three-dimensional structure. FTIR and DSC graphs confirmed that oxygen atoms were bound to GO with the formation of carboxylic, hydroxyl, epoxide, and carbonyl groups as a result of the oxidation of graphite, and GO was successfully synthesized. Additionally, these analyses showed that MTX and FA bind physicochemically to the structure of GO. The in vitro Franz diffusion test was performed as a release kinetic test. The release kinetics mathematical model and correlation coefficient (R2) of MTX-loaded GO/FA nanomaterials were found to be the Higuchi model and 0.9785, respectively. Stiffness analyses showed that adding FA to this release system facilitated the entry of the drug into the cell by directing the system to target cells. As a result of the stiffness analyses, the stiffness values of the control cell group, free MTX, and MTX/FA/GO applied cells were measured as 2.34 kPa, 1.87 kPa, and 1.56 kPa, respectively. According to these results, it was seen that MTX/FA/GO weakened the cancer cells. Combined use of the MTX/FA/GO drug delivery system had a higher cytotoxic effect than free MTX on the MDA-MB-231 breast cancer cell line. The results showed that the synthesized MTX/FA/GO material has promising potential in cancer cell-specific targeted therapy for MTX as a drug delivery system. Full article

The massive stockpiling of electrolytic manganese residue (EMR) has caused serious environmental pollution. In this study, EMR, coal gangue (CG), and fly ash (FA) were used as raw materials to obtain the optimal mix ratio based on Design-Expert mixture design. The effects of activator modulus, liquid–solid (L/S) ratio, and curing temperature on the mechanical properties of geopolymers were investigated. The results showed that the compressive strength of the prepared geopolymer was 12.0 MPa, and the 28d leaching of Mn was 0.123 mg/L under the conditions of EMR:CG:FA = 0.43:0.34:0.23, L/S = 0.9, a curing temperature of 60 °C, and a curing time of 24 h. This indicates that the geopolymer is an environmentally friendly material with high compressive strength. The mineral composition of the geopolymer is mainly hydrated calcium silicate and geopolymer gel. In addition, a more stable new mineral phase, MnSiO₃, was generated. The Fourier transform infrared (FTIR) spectrogram showed that the peak at 1100 m⁻¹ was shifted to 1112 cm⁻¹, which indicated that a geopolymerization reaction had occurred. Through scanning electron microscopy (SEM) and energy dispersive spectrum (EDS) analysis, it was identified that the geopolymerization produced a large amount of amorphous gelatinous substances with a relatively dense structure, the major elements being oxygen, silicon, aluminum, calcium, and sodium. Full article

Arbidol hydrochloride is an antiviral product widely used in Russia and China for the treatment of, among other diseases, influenza. In recent years, it has turned out to be highly effective against COVID-19. However, there is little knowledge about its physicochemical properties and its behavior in the presence of various pharmaceutical excipients, which could be useful in the development of new preparations by increasing its solubility and bioavailability. For this reason, binary mixtures composed of arbidol hydrochloride and selected pharmaceutical excipients such as chitosan, polyvinylpyrrolione K-30 and magnesium stearate were prepared and subjected to differential scanning calorimetry (DSC), thermogravimetry combined with Fourier transform infrared spectrometry (TGA-FTIR) and Fourier transform infrared spectrometry (FTIR) analyses. In order to obtain clarity in the interpretation of the outcomes, chemometric calculations with factor analysis (FA) were used. Additionally, a powder X-ray diffraction (PXRD) and an intrinsic dissolution rate study were performed for arbidol hydrochloride itself and in the presence of excipients. As a result of the study, it was revealed that arbidol hydrochloride may undergo polymorphic transformations and be incompatible with chitosan and magnesium stearate. However, mixing arbidol hydrochloride with polyvinylpyrrolidone K-30 guarantees the obtaining of durable and safe pharmaceutical preparations. Full article